DE29706494U1 - Device for damped braking of two bodies moving relative to each other - Google Patents

Description

G 17 917 - lead 4 April 1997

Festo KG, Ruiter Strasse 82, 73734 Esslingen

Device for the damped braking of two bodies moving relative to each other

The invention relates to a device for the damped braking of two bodies executing a reciprocating linear movement relative to one another when their two end positions are reached, whereby a damping unit held on one body and cooperating with a stop surface provided on the other body becomes effective when the respective end position is approached.

A device of this type is, for example, evident from the German utility model G 94 16 52 3. It is implemented there in connection with a rodless linear drive. This has a first body formed by a driven slide, which is guided axially displaceably on a second body formed by the housing of the linear drive. When the linear drive is in operation, the slide carries out a linear movement back and forth. The two end positions of the slide are specified by two stop units onto which the slide can run. In order to dampen the impact when the end position is reached, two damping units formed by shock absorbers are provided.

which become effective before the respective end position is reached and mitigate the impact of the slide on the respective stop unit.

There is nothing to criticize about the effectiveness of the known device. However, the construction is relatively complex and correspondingly expensive.

The invention is therefore based on the object of creating a device of the type mentioned at the outset which enables more cost-effective production with a simple structure.

To solve this problem, it is provided that a damping unit responsible for the damped braking in both directions of movement is provided on one body, which is arranged axially between two impact members, each having an impact surface, wherein the impact surfaces point in opposite axial directions and each face a stop surface connected to the other body, and that each impact member normally assumes a basic position supported axially immovably towards the associated stop surface, from which it can be deflected upon impact with the associated stop surface with axial shortening of the damping unit supported by the other impact member in the basic position.

This means that end position damping that is effective in both directions of movement is still possible, although only one damping unit is required instead of the two damping units previously required.

This damping unit is effective in both directions of movement. When the end position is approached, the impact element arranged at the front hits the stop surface provided on the other body and is thereby displaced relative to the body supporting it in the direction of the damping unit, which experiences an axial reduction in length because it is supported on the opposite side by the impact element supported in the basic position on the body supporting it. This effect occurs in both directions of movement, with only the functions of the two impact elements being swapped. Apart from the lower manufacturing costs, this design also has the advantage that the same damping properties are present in both directions of movement without complex adjustment work. The device according to the invention can be used in all devices that have two bodies that move relative to one another. Their use appears to be particularly useful in connection with fluidically and/or electrically operated linear drives and in particular in linear drives in which a linearly displaceable carriage is to be braked gradually rather than suddenly when it reaches its two end positions.

Advantageous further developments of the invention emerge from the subclaims.

The damping unit is expediently formed by a fluidic shock absorber, which can have a conventional structure with a damper housing and a bumper that protrudes axially from it.

the housing can interact with one impact member and the bumper with the other impact member.

The impact members are expediently designed as separate components from the shock absorber, so that a commercially available shock absorber can be used. However, an embodiment would also be conceivable in which the impact members are formed from components of the shock absorber itself, for example from parts of the damper housing and the bumper.

The use of a fluidic shock absorber as a damping unit is particularly suitable when a hard impact is to be expected due to high relative speeds or masses that are difficult to move. Alternatively, and this is particularly the case for applications with less impact in the end positions, a simple rubber-elastic buffer body could also be provided as a damping unit. In all cases, it is advantageous if the impact elements are held in their basic positions by the damping unit itself under at least a slight preload, so that no additional return means are required.

The stop surface interacting with the impact elements is expediently part of a stop unit that specifies the respective end position.

In order to enable variable specification of the end positions, a respective stop unit can be arranged on the body supporting it so that it can be adjusted in the direction of movement of the two bodies.

In order to ensure that the stop unit is securely fixed to the associated body even in the event of a strong impact, surface teeth, e.g. in the form of ribbing, can be provided on the underside of the stop unit, which engage with transverse teeth extending in the direction of adjustment on the body carrying the stop unit. This results in a positive locking in the direction of movement of the two bodies between the stop unit and the body carrying it in every position of the stop unit.

In particular, if the device is used in a rodless linear drive which has a drive part arranged in a housing and an output part arranged to be displaceable outside the housing and coupled to the drive part via a driver passing through a longitudinal slot in the housing, the arrangement is expediently such that the driver has a fork part, between the fork legs of which the damping unit with the impact members is held, whereby the impact members can protrude outwards through openings in the fork legs in the direction of the associated stop surfaces.

The invention is explained in more detail below with reference to the accompanying drawings, in which:

Figure 1 is a plan view of a device equipped with a preferred design of the device according to the invention.

equipped linear drive, partly in section according to section line I-I in Figure 2,

Figure 2 shows a cross-section through the arrangement of Figure 1 according to section line II-II,

Figures 3 and 4 show the section of the linear drive from Figure 1 relating to the device according to the invention in the two possible end positions, and

Figure 5 shows an alternative design of the damping unit used in a representation corresponding to Figures 3 and 4.

The figures show a linear drive 1, generally designated 1, actuated by fluid force, which is equipped with a device, referred to below as a damping device 2, which serves to brake two bodies 4, 5, which execute a reciprocating linear movement relative to one another, indicated by the double arrow 3, when they reach their two end positions shown in Figures 3 and 4.

One body of the embodiment, hereinafter referred to as the second body 5, is the housing 6 of the linear drive 1. The other body, hereinafter referred to as the first body 4, is formed by the output part 7 of the linear drive 1, which is guided axially displaceably relative to the housing 6 via a linear guide device 8 that specifies the direction of the linear movement 3.

The output part 7 of the embodiment is designed like a slide and has a first guide part 9 on its underside, which overlaps a guide rail 12 fixed to the housing 6 in a similar way to a clamp. Between the guide part 9 and the guide rail 12 there is a bearing device 13, which is designed as a plain bearing device or preferably as a roller bearing device and ensures that the output part 7 can be guided precisely and yet moved easily.

The output part 7 has fastening holes 14 or other fastening means that make it possible to releasably fix a load to be moved, for example a component to be positioned.

The linear drive 1 of the embodiment is designed as a rodless linear drive. It has a cylinder chamber 15 inside the housing 6, in which a drive part 16 formed by a piston is accommodated so that it can move axially. Sealing elements 17 at the ends of the drive part 16 result in a fluid-tight division of the cylinder chamber 15 into two working spaces 18, 18', which can be pressurized with compressed air and/or vented via fluid channels not shown in detail. Hydraulic operation would also be possible. In this way, the drive part 16 can be caused to perform a linear movement 3 in one or the other axial direction.

The drive part 16 is coupled in terms of movement to the driven part 7. This is done in the embodiment by a driver 21, which is attached to the drive part 16 and protrudes through a longitudinal slot 22 from the cylinder chamber 15 and is attached to the driven part 7 located outside the housing 6. The longitudinal slot 22 passes through the housing wall enclosing the cylinder chamber 15 at one point on its circumference and extends linearly in the longitudinal direction of the housing 6 parallel to the linear movement 3.

If the drive part 16 is caused to move linearly, this movement is immediately followed by the coupled output part 7.

A rubber-elastic sealing band 23 is arranged within the cylinder chamber 15 in the area of the longitudinal slot 22, which axially rests on both sides of the drive part 16 on the flanks of the longitudinal slot 22 and seals it off. The sealing band 23 is guided inwards axially within the two seals 17 arranged at the ends of the drive part 16 in order to enable the driver 21 to reach through the longitudinal slot 22.

The linear drive 1 could also be an electrically operated linear drive. The drive part 16 could, for example, be formed by a component provided with a thread that runs on a spindle driven by an electric motor, or by a toothed belt running around deflection rollers.

In the embodiment, the driver 21 has a U-shaped fork part 24, the two fork legs 25 of which are arranged at an axial distance from one another and protrude towards the output part 7 and which is fastened to the drive part 16 in the middle area of its connecting web 26 by means of screws 27. The open side of the fork space 27 enclosed between the fork legs 25 therefore points towards the output part 7.

The output part 7 has a longitudinally continuous receptacle 28 on the side facing the driver 21. This has a slot-like opening 32 running longitudinally towards the driver 21 and open towards both end faces of the output part 7, through which the driver 21 reaches with its fork legs 25, so that these lie with their free end sections 33 within the receptacle 28.

In comparison to the section of the fork parts 24 which passes through the opening 32, the end sections 33 can be widened and in particular have a contour adapted to the cross-sectional shape of the receptacle 28.

In order to couple the driven part 7 to the driver 21 in an axially immovable manner, the end sections 33 are each acted upon by a holding element 34 on their axially opposite surfaces, which is supported on the first body 4 or the driven part 7 forming it. The holding elements 34 are expediently designed as screw members 34', which

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dimension Figures 1 and 2 have an external thread, via which they are screwed into the circular cylindrical contoured receptacle 28, which is provided with an internal thread 35 at least in its front end areas. The circumferential extent of the opening 32 is selected such that a sufficiently large wrap angle of the internal thread 35 is present in order to be able to securely fix the screw elements 34'.

By screwing the two screw links 34' from the opposite sides against the two fork legs 25, an axially play-free connection is created between the driver 21 and the output part 7.

In order to be able to specify the two axial end positions of the output part 7, which can be displaced relative to the housing 6, a housing-fixed stop unit 36 is provided on the housing 6 axially on both sides of the output part 7. It is usually located near one of the front end areas of the housing 6. In the exemplary embodiment, the stop units 36 are located on an extended housing leg 37 extending transversely to the direction of movement, on which the guide rail 12 of the guide device 8 is also arranged.

Each stop unit 36 has a stop surface 38 on the side facing the output part 7, which is located in the displacement path of the output part 7. It interacts with a counter stop surface 38' provided on the output part 7 to specify the assigned end position of the output part 7. The latter is located in the embodiment on the fork

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leg 25 opposite axial end face of the respective holding element 34, which therefore rests against the stop surface 38 of the facing stop unit 36 when the end position is reached, as shown in Figures 3 and 4.

The two possible end positions are variably adjustable in the embodiment. To do this, the stop units 3 6 can be adjusted in the direction of movement 3 of the two bodies 4, 5 on the body 5 that supports them and can be releasably locked in the desired positions using a fastening screw 42. The fastening screw 42 works together with a sliding block (not shown in detail) that is housed in an anchoring groove 43 that runs lengthways in the housing leg 37 and can be moved axially in this groove.

Additional screws 41 can also be anchored in the anchoring groove to secure the housing to a supporting structure.

In order to prevent an unintentional adjustment of the stop units 36 even in the event of a strong impact of the output part 7, additional positive locking measures are provided between the stop unit 36 and the housing 6. Each stop unit 36 has a surface toothing (not shown in detail) on its underside facing the housing leg 37 with alternating elevations and depressions in the direction of movement 3, which each extend transversely to the direction of movement 3 and to the longitudinal direction of the anchoring groove 43. A transverse toothing 44 complementary to this is located on the

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impact units 36 facing the top of the housing leg 37. It also has transverse elevations and depressions that are arranged one after the other in the longitudinal direction of the linear drive 1, so that, according to Figure 1, a complete toothing strip is produced that can extend over the entire length of the housing 6. It is divided into two partial strips by the anchoring groove 43, for example. The toothing does not need to be very deep, it can be relatively easy to produce grooves or knurls.

In order to specify a desired end position, the stop units 36 are initially roughly arranged in a stop position that approximately corresponds to the desired end position specification. The teeth then engage with one another in a form-fitting manner and provide a form-fitting support of the stop unit 36 with respect to the housing 6 in the direction of movement 3. After the fastening screw 42 has been tightened, a stop part 46 carrying the stop surface 38 is finely adjusted via a fine adjustment mechanism 45 until the desired end position specification is reached.

The stop surfaces 38 have the further purpose of working together with components of the damping device 2 arranged on the output part 7 in order to reduce the speed of the output part 7 during the last partial travel of the output part 7 before reaching the end position and to reduce the impact of the surfaces 38, 38'.

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For this purpose, the damping device 2 has a damping unit 47 arranged on the first body 4 or on the output part 7, which is responsible for the damped braking of the output part 7 in both the one and the other direction of movement. A single damping unit therefore causes end position damping on both sides or in both directions of movement.

The damping unit 47 is located axially between two impact members 48,48', whereby in the embodiment they are held together with these in the fork space 27 of the fork part 24. The impact members 48,48' protrude axially outwards with an impact tappet 53 through an associated opening 54 in the adjacent fork leg 25 and a central opening 55 in the holding element 34 that is aligned with this. A support section 52 of the impact members 48,48', which has a larger diameter and is, for example, piston-like, is located within the fork space 27 and rests against the inner surfaces of the fork legs 25 in the normally assumed basic position according to Figure 1. In this basic position, the impact plungers 53 protrude beyond the holding elements 34, so that an impact surface 56 provided on their free front side is positioned in front of the counter-stop surface 38' at a distance from the stop surface 38.

The damping unit 47 is under a certain axial preload and simultaneously acts on both impact elements 38,38', so that they normally, i.e. as long as the impact surfaces 56 do not make contact with the stop surfaces

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surfaces 38, assume the aforementioned basic position in which they are supported axially immovably with respect to the first body 4 via their support section 52 towards the associated stop surface 38.

The coupling of the output part 7 and driver 21 is carried out simply by axially pushing the damping unit 47 and impact members 48, 48' fixed to the fork part 25 into the receptacle 28 until the desired relative axial position according to Figure 1 is reached. One of the screw members 34' can already be screwed in. The second screw part 34' is then also screwed in and the fork part is clamped.

In the embodiment of Figures 1 to 4, the damping unit 47 is designed as a fluidic shock absorber 57. It has a suitably cylindrical damper housing 58 in which a damping piston 62 is arranged, which is engaged by a bumper 63 which extends out from one end of the damper housing 58 and which can be moved together with the damping piston 62 relative to the damping housing 58. A certain preload of the bumper 63 in the extension direction is achieved by means of a spring device (not shown in detail), so that this preload causes the bumper 63 to press against the back of one impact member 48 and the base 60 of the damper housing 58 to press against the back of the other impact member 48.

The damping unit 47 is held axially displaceably on the first body 4. This is achieved in the embodiment by the shock absorber 57 being

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• *
t

with its cross-sectional dimensions appropriately adapted holder 28 is inserted with sliding play, whereby the
slot-like opening 32 is so narrow that the damping unit 47 cannot pass through to the outside.

The cross-sectional shape of the support sections 52 of the impact members 48,48' may correspond approximately to that of the damper housing 58,
so that the impact members 48,48' formed separately from the damping unit 47 can also be easily moved relatively
to the first body 4 in the holder 28.

At this point it should be noted that the impact elements
48,48' could also be formed by solid components of the bumper 63 and the damper housing 58. For example, one impact member 48 could be formed by the front end section of the bumper 63 and the associated support section 52 by a radial projection
of the bumper, for example a locking ring or a cross pin. The other impact member 48' could be formed by an extension of the bottom 60 of the damping housing 58 or by the bottom 60 itself, in the latter
In case the associated stop surface 38 could be arranged on the front side of a rod or tube which is
can act on the floor 60 through the openings 54,55.

If during operation the output part 7 shifts relative to the housing 6 and moves, for example, to the left in Figure 1
is initially a movement with the usual working speed
If the output part 7 approaches the

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left-hand stop unit 36, the impact surface 56 of the impact member 48 eventually comes into contact with the facing stop surface 38. Due to the kinetic energy of the output part 7, this is displaced further in the direction of the stop unit 36, whereby the impact member 48 is displaced axially in the direction of the damping unit 47 relative to it by the stop surface 38 acting on it. Since the damper housing 58 is supported axially immovably with respect to the first body 4 via the oppositely arranged impact member 48', the bumper 63 is pushed into the damper housing 58, within which the displacement of a damping fluid takes place in a manner known per se, resulting in a counteracting damping force that opposes the impact member 48 with a certain flexible resistance. This results in the output part 7 being braked during the pushing back of the push rod 63 until the end position is reached by the counter stop surface 38· against the stop surface 38. This situation is shown in Figure 3.

If the output part 7 is subsequently displaced in the opposite direction, the spring-loaded bumper 63 can extend again and return the impact member 48 assigned to it to the basic position shown in Figure 1.

When moving into the opposite end position, the impact member 48' on the right in Figure 1 interacts with the stop surface 38 facing the tension and is thereby also displaced axially in the direction of the damping unit 47. Since the impact member

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impact member 48' acts on the damper housing 58, this is displaced relative to the stationary bumper 63 supported by the left impact member 48 in the basic position, whereby the bumper 63 moves into the damper housing 58 again while displacing the damping piston 62 and the damping process described above also takes place. The situation when the end position is reached is shown in Figure 4.

If the output part 7 then moves out of the end position again, the damper housing 58 pushes the impact member 48' back into the basic position according to Figure 1.

During the damping process, an axial shortening of the damping unit 47 takes place, which on the one hand is acted upon by one of the impact elements and on the other hand is supported by the other impact element supported in the basic position.

Figure 5 shows that instead of a fluidic shock absorber, another type of damping unit 47 can also be used. Figure 5 shows a damping unit 47 that is formed by a rubber-elastic buffer body 64 that can be axially compressed in a rubber-elastic manner. The axial length of the buffer body 64 is selected according to the desired damping properties, as is the material properties. It could, for example, be made of rubber or an elastomer material.

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The buffer body 64 is expediently arranged in the holder 28 in a manner comparable to the pneumatic, hydraulic or combined pneumatic-hydraulic shock absorber 57, whereby it can be loosely inserted or pushed into the holder 28. As with the shock absorber 57, the impact members 48, 48', which are made of metal in particular, can be designed as components separate from the buffer body 64, which rest loosely under pre-tension on the end faces 65 of the buffer body 64. Alternatively, the impact members 48, 48' could also be firmly connected to the buffer body 64, for example by being firmly connected to the buffer body 64 with their piston-like support section 52 by gluing or vulcanization.

In the embodiment, the stop surfaces 38 serve both to interact with the impact members 48, 48' and, for the purpose of specifying the respective end position, to interact with the counter stop surfaces 38'. This is particularly advantageous in the present case because the impact surfaces 56 on the end faces of the impact members 48, 48' are arranged concentrically within the annular counter stop surfaces 38' provided on the holding elements 34, 34', so that a particularly space-saving structure is obtained. However, it would be entirely possible to provide separate stop surfaces 38 on the second body 5 or housing 6 for the impact surface 56 and the counter stop surface 38', in particular if the impact surface 56 and the counter stop surface 38' are arranged next to one another transversely to the direction of movement 3.

Claims (16)

G 17 917 - lead 4. April 1997 Festo KG, Ruiter Straße 82. 73734 Esslinqen Device for the damped braking of two bodies moving relative to each other CLAIMS 1. Device for the dampened braking of two bodies (4, 5) performing a reciprocating linear movement relative to one another when they reach their two end positions, whereby when the respective end position is approached, a damping unit (47) held on one body and cooperating with a stop surface (38) provided on the other body becomes effective, characterized in that a damping unit (47) responsible for the dampened braking in both directions of movement is provided on one body (4, 7), which is arranged axially between two impact members (48, 48·) each having an impact surface (56), whereby the impact surfaces (56) point in opposite axial directions and each face a stop surface (38) connected to the other body (5, 6), and that each impact member (48, 48») normally assumes a basic position supported axially immovably towards the associated stop surface (38), from which, when it hits the associated stop surface (38), causes axial shortening of the · O ·· The the damping unit (47) supporting the other impact member located there. 2. Device according to claim 1, characterized in that the damping unit (47) is formed by a fluidic shock absorber (57). 3. Device according to claim 2, characterized in that the shock absorber (57) has a damper housing (58) and a bumper (63) protruding from it and displaceable relative to the damper housing (58), wherein the one impact member (48·) cooperates with the damper housing (58) and the other impact member (48) with the bumper (63) and wherein both the bumper (63) and the damper housing (58) are arranged to be axially movable relative to the body (4,7) carrying the damping unit (57). 4. Device according to claim 3, characterized in that the impact members (48, 48') are designed as separate components with respect to the shock absorber (57) and flank the shock absorber (57) axially on both sides. 5. Device according to claim 1, characterized in that the damping unit (47) is formed by a buffer body (64) having rubber-elastic properties. 6. Device according to one of claims 1 to 5, characterized in that the impact members (48, 48·) are held in their basic positions by the damping unit (47) under axial prestress. 7. Device according to one of claims 1 to 6, characterized in that each stop surface (38) is part of a stop unit (36) specifying the relevant end position. 8. Device according to claim 7, characterized in that at least one stop unit (36) for specifying different end positions in the direction of movement (3) of the two bodies (4, 5) is adjustably arranged on the body (5) carrying it. 9. Device according to claim 8, characterized in that the at least one stop unit (36) has a surface toothing on its underside facing the body (5) supporting it, which surface toothing engages with a transverse toothing (44) extending in the adjustment direction of the body (5) supporting the stop unit (36) for the positive fixing of the set stop position. 10. Device according to one of claims 1 to 9, characterized in that the damping unit (47) is connected to the output part (7) of a linear drive (1). 11. Device according to claim 10, characterized in that the linear drive (1) has a fluidically and/or electrically displaceable drive part (16) which is coupled in terms of movement to the output part (7) via a driver (21), wherein the damping unit (47) is placed in the coupling region between the driver (21) and the output part (7). 12. Device according to claim 11, characterized in that the driver (21) has a fork part (24), between whose fork legs (25) the damping unit (47) with the impact members (48, 48') is held, the impact members (48, 48') projecting axially outward through openings in the fork legs (37) in the direction of the stop surfaces (38). 13. Device according to claim 12, characterized in that the fork part (24) engages with the end sections (33) of its fork legs (25) in a receptacle (28) which extends longitudinally through the output part (7) and is open at one point on its circumference, the end sections (33) being axially loaded on their axially opposite surfaces by a holding element (34) which is designed in particular as a screw member (34') and fixed to the output part (7). 14. Device according to claim 13, characterized in that the holding elements (34) are penetrated by the impact members (48, 48·) in an axially movable manner. 15. Device according to one of claims 1 to 14, characterized in that one of the two bodies (5) is formed by the housing (6) or a component of a linear drive (1) connected thereto and the other of the two bodies (4) is formed by the output part or a component of the linear drive (1) connected thereto. 16. Device according to claim 15, characterized in that the linear drive (1) is designed in a rodless design and has a housing (6) forming one of the bodies (5). in which a fluidically and/or electrically displaceable drive part (16) is arranged, on which a driver (21) penetrating a longitudinal slot (22) of the housing (6) engages, which is coupled outside the housing (6) to a slide-like output part (7) forming the other of the two bodies (4) and enabling the fastening of a load to be moved.